Topofthe mopheads
Give VIP treatment to get regal blooms
All garden owners want plants that give the garden a lift. Hydrangeas, with their mopheads of pink, red, white or blue, in many ways are that plant. But their requirements need to be a little better understood.
They produce a superb display from July to September and later if the weather permits. They were discovered in China in 1767 and can lift a garden from the mundane to the regal.
Things have become a little confusing recently as hydrangeas also appear as a supposed ‘house plant’, forced on by growers to give a colour display ahead of there normal midsummer flowering time. The plant is not comfortable in this environment and, often placed in strong sunlight, quickly goes into a decline. This gives the hydrangea an unfair image of a difficult plant. A further dilemma created by the ‘forced hydrangeas’ is, if they are put outdoors after purchase in March or April, the cold forces them into an almost certain terminal decline after the mollycoddling in greenhouses.
The key to understanding this plant lies in the origins of its name, from Greek hudro- ‘water’ + angeion ‘vessel’ (from the cup shape of its seed capsule). If planted where water is available, in a damp area, then it will be off to a good start. Hydrangeas that have been grown outdoors are nearly all very hardy, especially if they get a little help and understanding.
The main species we see in Ireland are macrophylla. If you cater for their needs, treating them like a VIP (Very Important Plant), they will respond well.
Selecting a part of the garden that has moist, well-drained soil in a cool, semi-shady spot will ensure that your hydrangeas excel. Providing enough shelter to avoid cold winds also helps. Avoid dry sunny spots. They will manage full sun but, as a general rule, some shade is far more helpful, especially
for white hydrangeas.
If the watering and feeding is handled correctly, then growing them in large pots is also an option. They look especially spectacular on patios. I will be planting a collection of white flowering hydrangeas in pots this summer on the shady side of my house where they will thrive and then will return them in the pots to the warmer, south facing side for the winter.
Pruning out the old, dead flowers is essential, but don’t do this in autumn. Wait for March, when the sap is starting to rise through the stems. It is best to leave the flowers on the plant over winter to provide some frost protection. You can then cut back to the first strong buds lower down the stem in spring.
Avoid pruning too hard but equally remember if left unpruned the hydrangea will produce a large number of flower heads the size of a tennis ball, all supported on old, unstable stems. Results are impressive when pruned correctly as the number of flower heads is reduced by about a quarter but the flower size is far greater.
The colour of the hydrangeas can be influenced by the soil. Test kits that show a pH reading of 7.0 means hydrangea will be pink, less than 7.0 and the blossoms will be blue. Composts and feeds may help adjust the soil to the required level. A tonic with aluminium sulphate and iron can help turn flower heads blue. Hydrangea colourant unlocks aluminium sulphate in the soil, turning pale-pink hydrangeas pale blue and dark-pink hydrangeas a dramatic deep mauve. There are 22 varieties, including arborescens, paniculata and serata, and a climber which looks spectacular against a large wall.